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. Menlo Park, in the county of Middlesex and be reached by the heat' of the filament. It is of bromine or iodine may as readily be used electric lamps.

In practice, however, I prefer to use the bi- UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, MENLO- PARK, NEW JERSEY, ASSIGNOR TO THE EDISON ELECTRIC LIGHT COMPANY, OF NEW YORK, N. Y.

METHOD OF MANUFACTURING ELECTRIC" LAMPS.

SPECIFICATION forming part of Letters Patent No. 395,962, dated January 8, 1889.

Application. filed September 22, 1882.

.To all whom it may concern:

Be it known that. I, THOMAS A. EDISON, of

State of New Jersey, have invented a new and useful Improvement in the Method of Manu-, facturing Electric Lamps, (Case No. 487,) of which the following is a specification.

The object of this invention is torender more rapid and effectual the process of exhausting-the inclosing-globes of incandescing I have found that if achloride, bromide, or. iodide of any element or a compound of any elements containing chlorine, bromine, or iodine, preferably in an anhydrous condition, is introduced within the globe, so that itwill be heated when the incandescing filament of the lamp is heated during the process of exhaustion, the time required in exhausting the lamps is lessened and a larger'number can be manufactured in a given time than has hitherto been possible. Such substance may be placed directly within the globe or in a bulb or chamber connected with the globe and forming temporarily a part thereof, where it can be heated by the heat of the filament; or itmay be placed on the filament itself or on the clamps by which such filament is connected to the leading-in wires. If placed in a' bulb connected with the globe, such bulb would be sealed off" after the lamp is exhausted. The three substances mentioned have similar advantages and produce similar results when used for this purpose, and any kind of chloride, bromide, or iodide may be used, or abichloride or even a terchloridesuch as the terchloride of chromium or similar compounds-bf bromine or iodinen|ay be used.

chloride of platinum, and to apply this by painting it on the clamps, where it can readily to be understood, however, that compounds in this way, and that such elements are for this purpose the equivalents of chlorine and of each other. The exhaust-ionof the globe is accomplished by means of a Sprengel or other mercury vacuum-pump, and an electric cur- Berial No. 72,527. (No specimens.

rent is used to heat the carbon filament of the lampto incandescence during the latter portion of such exhaustion.

The chlorine, bromine, or iodine given off during exhaustion combines with the mercury vapor which enters the lamp-globe from the pump, forming a mercury compound, and mercury vapor being thus eliminated from the atmosphere of the globe the process of exhaustion is quickened and a higher vacuum is obtained, and electrical carrying between the filament. and the glass, which the presence of mercury vapor assists, is avoided. The mercury compounds formed being solid, of course have no vapor tension and do not reduce the vacuum.

What I claim is 1. The process of producing a high vacuum in theinclosing-globe of an incandescing electric lamp,.consisting in placing within said globe a compound of chlorine or equivalent element and then withdrawing the air from said globe, the filament-of the lamp being heated to incandescence by an electric current during a portion of the latter step, substantially as set forth.

2. The process of producinga high vacuum in the inclosing-globe of an incandescing electric lamp, consisting in placin g within the lamp aquantity of biehloride of platinum and then withdrawing the air from said globe, the filament of the lamp being heated to incandescence by an electric current duringa portion of the latter step, substantially as set forth.

3; The process of producing a high vacuum in the inclosing-globe of an 'incandescing electric lamp, consisting in placing on the clamps which hold the'filaluent of said lamp a quantity of bichloride of platinum and then withdrawing the air from said globe, said filament being heated to incaudescence by an electric current during a portion of the latter step, substantially as set forth. I

This specification signed and witnessed this 16th day of September, 1882.

THOS. A. EDISON \Vitnessest.

H. W. SEELY, R. N. DYEB. 

